# HG changeset patch
# User rkennke
# Date 1478702729 -3600
#      Wed Nov 09 15:45:29 2016 +0100
# Node ID 85ec919f4e30693dc42748cdfde5c700f38463dd
# Parent  c8138d5377a44ccbab3ea757e16d8ca58d16c23a
[mq]: cancel.patch

diff --git a/src/share/vm/gc/shenandoah/shenandoahConcurrentMark.cpp b/src/share/vm/gc/shenandoah/shenandoahConcurrentMark.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahConcurrentMark.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahConcurrentMark.cpp
@@ -882,14 +882,21 @@
                                                     ParallelTaskTerminator* terminator) {
   ShenandoahHeap* heap = ShenandoahHeap::heap();
   int seed = 17;
-  while (true) {
-    if (heap->cancelled_concgc()) clear_queue(q);
-    if (heap->cancelled_concgc() ||
-        (!try_queue(q, cl) &&
-         !try_draining_an_satb_buffer(q) &&
-         !try_to_steal(worker_id, cl, &seed))
-        ) {
-      if (terminator->offer_termination()) break;
+  bool terminate = false;
+  uint stride = ShenandoahMarkLoopStride;
+  while (! terminate) {
+    if (heap->cancelled_concgc()) {
+      clear_queue(q);
+      while (! terminator->offer_termination());
+      return;
+    }
+    for (uint i = 0; i < stride && ! terminate; i++) {
+      if (!try_queue(q, cl) &&
+          !try_draining_an_satb_buffer(q) &&
+          !try_to_steal(worker_id, cl, &seed)
+          ) {
+        if (terminator->offer_termination()) terminate = true;
+      }
     }
   }
 }
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeap.cpp b/src/share/vm/gc/shenandoah/shenandoahHeap.cpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeap.cpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeap.cpp
@@ -2052,8 +2052,7 @@
   // only report it once
   if (!_cancelled_concgc) {
     log_info(gc)("Cancelling GC");
-    _cancelled_concgc = true;
-    OrderAccess::fence();
+    OrderAccess::release_store(&_cancelled_concgc, true);
     _shenandoah_policy->report_concgc_cancelled();
   }
 
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeap.hpp b/src/share/vm/gc/shenandoah/shenandoahHeap.hpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeap.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeap.hpp
@@ -124,7 +124,7 @@
   HeapWord** _top_at_mark_starts;
   HeapWord** _top_at_mark_starts_base;
 
-  bool _cancelled_concgc;
+  volatile jbyte _cancelled_concgc;
 
   jbyte _growing_heap;
 
diff --git a/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp b/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp
--- a/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp
@@ -188,7 +188,7 @@
 }
 
 inline bool ShenandoahHeap::cancelled_concgc() const {
-  bool cancelled = _cancelled_concgc;
+  bool cancelled = (bool) OrderAccess::load_acquire((jbyte*) &_cancelled_concgc);
   return cancelled;
 }
 
diff --git a/src/share/vm/gc/shenandoah/shenandoah_globals.hpp b/src/share/vm/gc/shenandoah/shenandoah_globals.hpp
--- a/src/share/vm/gc/shenandoah/shenandoah_globals.hpp
+++ b/src/share/vm/gc/shenandoah/shenandoah_globals.hpp
@@ -101,6 +101,9 @@
           "(ignored otherwise). Defauls to 0%.")                            \
           range(0,100)                                                      \
                                                                             \
+  experimental(uint, ShenandoahMarkLoopStride, 1000,                        \
+          "How many items are processed during one marking step")           \
+                                                                            \
   experimental(bool, ShenandoahConcurrentCodeRoots, false,                  \
           "Scan code roots concurrently, instead of during a pause")        \
                                                                             \